Synovial fluid basic calcium phosphate (BCP) crystals are common in osteoarthritis and are associated with severe degenerative arthropathies, characterized by synovial hypertrophy and non-inflammatory destruction of matrix-rich articular structures including cartilage, ligament and tendon. BCP crystals are responsible for mitogenesis in synovium and induce metalloprotease (MP) synthesis and secretion, thus promoting tissue damage. The goal of this project is to characterize the molecular mechanisms of BCP crystal-induced cell activation which result in I) mitogenesis and 2) MP secretion. The specific aims are to; 1) Examine the role of crystal dissolution, 2) Study the requirement of the proto-oncogenes (c-fos and c- jun) and the transcription factor AP-1, 3) Study the role of protein kinase C and 4) Investigate the role of the transcription factor nuclear factor kB 9NF-kB). MP (collagenase, stromelysin and gelatinase) induction will be identified using Northern blot, Western blot and enzyme assays. The role of proto- oncogenes will be studied using cDNA probes and anti-sense technology. The role of PKC will be studied by examining the effect of PKC inhibitors on BCP crystal-induction of MP production and secretion. The role of AP-1 and NF-KB will be studied using electrophoretic mobility shift assays. Transfection and CAT gene expression will be used in studies of gene regulation. The long-term goal of this research is to better understand the pathogenesis of BCP crystal-induced joint destruction thus allowing the development of rational drug treatment.